利用TTI法恢复原始地层厚度实例

有机质在还原环境沉积以后,随着埋藏深度的增加和时间的增长,其成熟度会不断提高,这是一个不可逆的过程。有机质的成熟度可用时间温度指数（TTI值）和镜质体反射率（R0）来表示。因此,在获得某一层位的TTI值（或R0值）和了解其埋藏史以后,便可恢复其原始地层厚度。本文详细介绍了TTI法恢复地层原始厚度的基本原理,并运用该方法对临清拗陷（东部）三叠系地层原始厚度进行了恢复。该方法的精度取决于地温和R0值、地质年龄等参数。     

用镜质体反射率资料恢复热史的相关问题及处理方法

利用镜质体反射率（R0）资料反演热史是否存在多解性取决于所采用的热流演化模型，采用目前常用的线性或指数模型，用R0作为检验标准，通过地史与热史的联合模拟，能够对持续沉降升温的含油气盆地的热史进行反演，R0不仅与温度及受热时间有关，而且与地层压力和镜质体的类型等因素有关，用TTI－R0法恢复烃源岩热演化，应当进行校正和氢指数校正，中提出了具体校正方法。     

利用PC—1500计算机编绘沉积埋藏史曲线及TTI值计算

本文以韦普赖斯—洛帕金法公式为理论依据,经推导获得TTI值计算公式。采用BASIC语言拟编程序,在PC—1500计算机实现编绘沉积埋藏史曲线和进入油气热演化各阶段的深度、时间、温度的门限值,为地质工作研究油气热演化史、生油期、运移期和油气远景资源预测提供可靠的基础数据。     

计算烃类成熟度史的实地TTI-Ro法

目前盆地模拟中重建烃类成熟度史时 ,一般只制作单一TTI(时间温度指数 ) Ro(镜质组反射率 )公式 ,不仅使成熟度史的误差较大 ,还有明显的概念错误。提出实地TTI Ro法 :首先根据地史模拟得到的埋藏史以及热史模拟得到的地温史求得TTI史 ,再根据实测的Ro以及各地层埋深最大时的TTI值 ,制作各地质时期的TTI Ro公式 ,此后便可求得烃类成熟度史。对比TTI Ro“通用公式”与中国临清坳陷某井和塔里木盆地某井的实地TTI Ro公式 ,差异很大 ,原因在于求取TTI史的公式假设有局限性 ,而由于干酪根的组分和化学键的复杂性 ,以及不同地区地质条件和生烃母质的差异性 ,不同地区的TTI生烃门限和TTI Ro公式都不同。应用TTI Ro法研究烃类成熟度史时 ,必须注意TTI的局限性和Ro的不良定标等问题。图 3表 4参9     

吐哈盆地中上三叠统储层钻前孔隙度定量预测

对控制吐哈盆地中上三叠统砂岩孔隙度的主要因素研究表明，热成熟度与砂岩孔隙度密切相关，而热成熟度的大小又受地温场和埋藏史的控制。TTI可以综合反映热成熟度，当TTI〉115时，中上三叠统砂岩将变得致密。中上三叠统砂岩发育渐进型埋藏、早缓晚快型埋藏和早快晚抬型三种埋藏方式，早缓晚快型埋藏最有利于孔隙保存。第一、二种埋藏方式的砂岩热成熟度与深度的关系较好，由此计算出吐鲁番坳陷中上三叠统有效储层深度下限平均为4100m。因此，提出砂岩热成熟度-孔隙度和热成熟度-深度的两个定量关系可以在钻前预测砂岩孔隙度和有效储层的保存下限深度。现场应用效果良好。     

吐哈盆地中上三叠统砂岩储集层钻前孔隙度定量预测

对控制吐哈盆地中上三叠统砂岩储集层孔隙度的主要因素研究表明,热成熟度与砂岩孔隙度密切相关,而热成熟度又受地温场和埋藏史的控制。时间-温度指数可以综合反映热成熟度。当时间-温度指数大于115时,中上三叠统砂岩将变得致密。中上三叠统砂岩发育渐进型埋藏、早缓晚快型埋藏和早快晚抬型3种埋藏方式,早缓晚快型埋藏最有利于孔隙保存。第1、第2种埋藏方式砂岩的时间-温度指数与深度的关系较好,由此计算出吐鲁番坳陷中上三叠统有效储集层深度下限平均为4100m.因此,依据砂岩储集层时间-温度指数与孔隙度和时间-温度指数与深度的两个定量关系,可以在钻前预测砂岩孔隙度和有效储集层的保存下限深度,现场应用表明,这种方法是可行的。     

TTI值在四川盆地有机质成熟度方面的应用

本文运用时间温度指数(TTI)法,根据四川盆地二叠系阳新统油气产状的实际资料,通过计算机处理,总结确定了有机质成熟度阶段的TTI特征值。并着重介绍TTI值与其它地化指标的相关关系,及其在有机质成熟度方面的应用。     

鄂尔多斯盆地剥蚀厚度恢复及其对上古生界烃源岩热演化程度的影响

运用镜质体反射率-深度剖面恢复出鄂尔多斯盆地中生界地层的剥蚀厚度,并结合烃源岩加热降温热模拟实验研究上古生界烃源岩的热演化特征。研究认为,反射率-深度剖面模型可分为3类,即单段式、双段式和三段式。盆地东部剥蚀厚度大,为1400～2200 m;西部剥蚀厚度小,为400～1000 m。据烃源岩时温互补热演化模拟实验,岩样在加热到一定温度后降温,随时间增加Ro值虽在增加,但Ro值增加速率不断降低,且在相同时间段内,降温幅度越大,生烃能力越低,当降温到一定程度时,随时间增加,生烃能力非常小。表明了源岩受热的时间尺度与热效应之间,温度起着主导作用。由于中东部剥蚀厚度远大于烃源岩热演化停滞时的最小剥蚀厚度,烃源岩热演化作用已处于停滞状态,西部剥蚀厚度较小的布1-天1地区,烃源岩的热演化作用在新生代仍有可能继续缓慢进行。     

TTI各向异性叠前深度偏移技术在库车复杂山地的应用

库车坳陷复杂山地地表地下双重复杂、地表高差大、山体发育、沟壑纵横,古近系膏盐岩挤压变形严重,厚度变化大,盐上浅层高陡,盐下目的层逆冲叠瓦断块发育,导致地震资料信噪比低,成像效果较差。通过多年复杂山地地震资料处理研究,形成了起伏地表TTI各向异性叠前深度偏移技术。叠前深度偏移速度建模中,采用了小平滑基准面,通过微测井约束层析反演计算静校正厚度、时间和速度,建立较高精度的浅表层速度模型;综合应用地表露头、重磁电、地质和钻测井资料约束建立了合理的中深层速度模型;采用井控TTI各向异性参数提取及网格层析成像技术提高了速度模型和成像的精度。通过TTI各向异性叠前深度偏移处理,库车坳陷复杂山地地震资料信噪比和成像质量明显提高,为区带研究及圈闭落实奠定了基础。     

苏北金湖凹陷生油岩热演化研究

本文运用地层压实校正法恢复金湖凹陷不同区块的地层埋藏史、生油岩埋藏史。根据镜质体反射率与古地温的关系,恢复了凹陷的古地温和古地温梯度,计算出生油岩在各地史时期的TTI值。      

用镜质体反射率资料恢复热史的相关问题及处理方法

利用镜质体反射率 (Ro)资料反演热史是否存在多解性取决于所采用的热流演化模型。采用目前常用的线性或指数模型 ,用 Ro 作为检验标准 ,通过地史与热史的联合模拟 ,能够对持续沉降升温的含油气盆地的热史进行反演。Ro 不仅与温度及受热时间有关 ,而且与地层压力和镜质体的类型等因素有关 ;用 TTI- Ro 法恢复烃源岩热演化 ,应当进行压力校正和氢指数校正 ,文中提出了具体校正方法     

沉积载荷致密排水对沉积盆地温度结构和成油窗口的影响

石油生成需要适当的温度条件,根据地热演化历史可以计算TTI值并定量估计成油窗口的位置.从而确定石油钻探需要达到的最大深度.本文根据盆地沉积史的地质资料和沉积物水文、热学和力学性质的实验室分析资料.对变形—孔隙水—热传输的非线性耦合问题进行了有限单元法计算.在不同而复杂的地质—热演化条件下,对地温、孔隙水压力和TTI值作出了全面估算.更加精确地确定了成油窗口的位置.     

GEOHISTORY, THERMAL HISTORY AND HYDROCARBON GENERATION HISTORY OF NAVARIN BASIN COST NO. 1 WELL, BERING SEA, ALASKA

Using a one-dimensional model, we numerically simulate with time the geological processes of sedimentary deposition, compaction, fluid flow, heat flow and hydrocarbon generation. Input well data, in the form of present-day formation thicknesses, porosity with depth, thermal gradient, vitrinite reflectance with depth, and fluid overpressure with depth constrain the dynamical model. We present model results for the Navarin Basin COST No. 1 well, including reconstructions of burial history, fluid flow history, thermal history and hydrocarbon generation history.
We also demonstrate how important geophysical variables (such as permeability, porosity, fluid pressure, fluid-flow rate, and thermal maturity indicators) vary with depth and time. Comparison of the model results with observed data illustrates and emphasizes the capabilities of the modelling procedure.
The significance of the dynamical model is that it permits a quantitative assessment to be made of (i) the timing and depth locations of the generation and migration of hydrocarbon in a basin, relative to the formation of structural and stratigraphic traps: (ii) the timing of the production of overpressuring and fracturing within a basin: and (iii) the effect of cementation and dissolution on the retention of hydrocarbons in a trap. The model also enables an assessment to be made of the most likely prospective areas for hydrocarbon accumulation in a basin.     

Ro反演的盆地热史恢复方法与相关问题

同一盆地不同深度的镜质体反射率(R_o)是盆地所受热流密度变化的反映。因此,可通过建立盆地的古热流、古地温及镜质体反射率模型来反映盆地演化历史。但是,R_o在多旋回盆地中存在多解性及不可逆性。所以,在用R_o进行盆地反演时,应从原始盆地恢复入手,最大限度地挖掘可靠的R_o资料;为了克服R_o的不可逆性及可掩盖性,可将lgR_o-H剖面进行分段综合解释,对于被不整合分隔的沉积层,分段求取平均R_o值作为该段的R_o值,对于突变的lgR_o-H曲线,则应注意局部火山活动的影响,剔除异常值;另外,盆缘露头及浅埋区的R_o资料则主要用于说明盆地演化早期的古地温场特征。     

RELATIONS BETWEEN DEPTH OF BURIAL, VITRINITE REFLECTANCE AND GEOTHERMAL GRADIENT

In wells where the drilled sequence is now at its maximum temperature, relations between depth and vitrinite reflectance show three segments: an upper segment with a linear gradient from 0.2–0.25% Ro at the surface to 0.6–0.7% Ro; a middle segment in which reflectance increases rapidly to c. 1.0% R; and a lower segment in which the gradient is again linear but reflectance increases more rapidly than in the upper segment. With a linear scale for depth, the inflection represented by the short middle segment tends to be obscured by the adoption by some authors of a log scale for reflectance.
The depth to the inflection systematically increases with decrease in geothermal gradient, allowing the development of a general diagram relating depth, reflectance and geothermal gradient. In wells where erosion is probable either at the present-day surface or at an unconformity, the general diagram can be used to estimate former maximum depths of burial and paleogeothermal gradients. These estimates, together with the presence of the inflection in the depth/reflectance relation, should be part of the input into modelling of the thermal history of sedimentary basins when reflectance is used in the model. The inflection is the result of the changing chemistry of vitrinite during oil generation, and the contrast between the depth/reflectance gradients above and below the inflection comparably reflects the contrast in vitrinite chemistry.     

利用流体包裹体计算地层剥蚀厚度——以东海盆地3个凹陷为例

绘制包裹体形成温度对埋藏深度的关系曲线,从明显的温度跃变之处可以确定侵蚀不整合面;把剥蚀面以下的深度、温度(或压力)对应数值的点用回归方法联结成的直线,向上延伸至古地表温度的坐标处,这一坐标也就是古地表面。对于浅埋藏阶段还未压实地层捕获的包裹体,必须经过压实系数校正才能进行。由剥蚀面至古地表面的距离就是地层剥蚀厚度,计算出东海盆地3个凹陷不同的地层剥蚀厚度。结果表明,本区第三系地层(E₂、E₃)大多数埋深刚刚达到或者完全进入主成熟高峰期门限,今后勘探应着重寻找沉积间断以前的有利构造圈闭;对于K、E₁和N₁地层,沉积间断以后比间断以前热演化稍微充分一些,因此对沉积间断以后的构造部位也应该加以重视。      

BURIAL AND THERMAL HISTORY MODELLING OF THE MURZUQ AND GHADAMES BASINS (LIBYA) USING THE GALO COMPUTER PROGRAMME

The GALO computer programme was used to model the thermal and burial histories of the Murzuq and Ghadames Basins, Libya. The model was based on recent drilling and seismic data from the basins, and used published deep temperature and vitrinite reflectance measurements. The model provides more accurate results than previous studies which were based on constant geothermal gradients during the basins' histories, and variations in heat flux at the base of the sedimentary cover were chosen so that calculated values of vitrinite reflectance coincide with those observed. The Murzuq Basin and Libyan part of the Ghadames Basin contain similar source rock units but have different burial histories. In the Murzuq Basin, maximum present‐day burial depths of Cambrian sediments range from 2200 to 2800 m and only locally reach 3000 – 3600 m; in the Ghadames Basin, however, burial depths can exceed 4–5 km. The burial history of the Murzuq Basin includes several periods of intense erosion and lithospheric heating which produced significant lateral variations in thermal maturity, leading in places to unexpected results. For example, relatively shallow‐buried Lower Silurian source rocks in the A‐76 area on the flank of the Murzuq Basin have a thermal maturity of R_o = 1.24% which is higher than the maturity of the same interval in more deeply buried areas (wells D1‐NC‐58 or J1‐NC101). In the central part of the Ghadames Basin, the modelling suggests a higher level of thermal maturity for organic matter in Silurian strata (R_o 0.8 to 1.3%), confirming the generation potential of Lower Silurian “hot shales”. Significant hydrocarbon generation began here in the Late Carboniferous and continues at the present day. Modelling of the Late Devonian (Frasnian) Aouinat Ouinine Formation “hot shales” suggests limited hydrocarbon generation depending strongly on burial depth, with the main phase of hydrocarbon generation taking place during the final episode of thermal activation in the Cenozoic. In the wells studied in the Ghadames Basin, the “oil window” extends over a considerable part of the present‐day sedimentary column.